A radula is an anatomical structure that is used by mollusks for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus
If by buffer you mean dilute or cancel out a 12 ph level is a base so you need to add the equal and opposite amount of acid to it....kind of like how -1+1=0
hope this helps im learning about this too!
Cardiac muscles is the answer
